CHAPTER – II
Surveys & Investigations
2.0 Main Components
As per the feasibility studies carried out by NWDA in 1995, the Ken-Betwa Link Project envisaged construction of the following components:-
I DAUDHAN DAM
1. An earth fill-cum-concrete dam across Ken River at Daudhan with FRL 287 m.
2. A tunnel (2km long) from the left bank of Daudhan dam for taking water to the Ken-Betwa link canal.
3. Power House-I (2x30 MW) to the left of the spillway at the toe of the dam.
4. Power House-II (2x6 MW) at the tunnel outlet.
II LINK CANAL
1. A link canal (231.45 km long including length of tunnel) with off take FSL 259 m to existing Barwasagar reservoir on Barwa nallah.
2. Cross-drainage/ Cross-masonry works (59 Nos.).
III UPPER BETWA PROJECT
Four projects in Upper Betwa basin (As proposed by Govt. of MP in their Master Plan).
a. A dam at Neemkheda across Betwa River.
b. A dam at Richhan across Richhan River, a tributary of Betwa River.
c. A dam at Kesari across Keotan River, a tributary of Betwa River.
d. A barrage at Barari across Betwa River.
Surveys and investigations were carried out for the above components at Feasibility Report stage except the projects in Upper Betwa basin, as their locations were tentative as per the Master Plan and were to be finalized by the state of Madhya Pradesh.
At the DPR stage, in light of the various detailed studies carried out through different expert organizations and also finalization of projects in Upper Betwa by MP, certain changes in the project planning have been made by NWDA. The Link Project now envisages construction of following components:-
I DAUDHAN DAM
1. An earth fill cum concrete dam across Ken river at Daudhan with FRL 288 m.
2. An upper level tunnel (1.929 km long including length of transition) about 170 m from the left bank of Daudhan dam for taking water to the link canal.
3. A lower level tunnel (1.1 km long) about 100 m from the left bank of Daudhan dam axis for taking water to the LBC of earlier proposed Ken Multipurpose Project.
4. Power House-I (2x30 MW) to the right of spillway at the toe of Daudhan dam.
5. Power House-II (3X6 MW) at the outlet of lower level tunnel.
II LINK CANAL
1. A link canal (220.624 km long including length of upper level tunnel) with off take FSL 257 m to existing Barwasagar with FRL 219.20 m across Barwa nallah, a tributary of Betwa river.
2. A 7.1 km long Barwa nallah to carry link waters from Barwa sagar to Betwa river at 12.75 km upstream of existing Parichha weir
3. A 2.1 km long canal for connecting Power House-II to Ken LBC at FSL 246.00 m
4. Ken LBC (57.3 km long, modified) proposed under Ken Multi Purpose Project (KMPP) (which is replaced by Daudhan dam)
5. A bye pass channel from lower level tunnel to meet irrigation requirements of Ken LBC when Power House-II will not be in operation.
6. Major Cross-drainage/Cross-masonry works (55 Nos.).
III UPPER BETWA PROJECTS
(a) Makodia dam:
(i) An earth fill cum concrete dam across Betwa river at Makodia village with FRL 437.5 m in place of Neemkheda dam about 7 km u/s of it.
(ii) Two canals (RBC-83.38 km & LBC-6.74 km).
(iii) Major cross drainage/cross masonry works (58 Nos.)
(b) Barari barrage:
(i) A barrage at Barari village across Betwa River with pond level 407.72 m located at about 69km d/s of Makodia dam.
(ii) A pipe line (4 km long) for lifting water by 21 m to an existing tank near village Gulabganj, Gulabganj tehsil in Vidisha district and there from to a ridge canal (4.7 km long) to irrigate the proposed command.
(iii)Major cross drainage/cross masonry works (2 Nos.)
(c) Kesari barrage:
(i) A barrage at Kesari village across Keotan river, a tributary of Betwa River with pond level 403.90 m.
(ii)A pipe line (2.9 km long) for lifting water by 8 m to proposed forebay reservoir near village Amera, Basoda tehsil in Vidisha district and a gravity canal (9.60 km long) from the forebay reservoir to irrigate the proposed command up to Chakra nallah near village Barwasa in Vidisha district.
2.0.1 Background for changes in DPR
The background behind making changes/not making any changes in various components proposed earlier in feasibility report is given below in brief:-
2.0.1.1 Daudhan dam and Spillway
While finalizing the location of dam site on Ken river, various alternatives for locating the dam both upstream and downstream of the existing Gangau weir had been considered in light of Ken Multipurpose Project Report (KMPP) prepared by the Water Resources Department, Govt. of M.P. Out of these alternatives, the option of locating the dam 2.5 km upstream of the existing Gangau weir near Daudhan village was finally selected by NWDA and details of surveys and investigations conducted at this site had been incorporated in the feasibility report of this link project prepared during March 1995. The dam site is located at latitude 24o36’51’’ N and longitude 79o50’30’’ E.
The location of dam site had again been reviewed jointly by the officials of CWC, GSI and NWDA in June, 2006 and it was decided after joint field visit to keep the location of dam axis same as finalized at the time of preparation of FR. It was, however, decided to explore the possibility of keeping the spillway at the centre of the river gorge instead of left bank of the river as proposed earlier in the FR. Accordingly, as per the suggestions of GSI, few exploratory holes in the river gorge for specified depth were drilled to find out the preconstruction geological conditions for locating the spillway at the center of the river gorge. After carrying out the mapping of the area & logging of the drill cores, GSI vide its preconstruction geological notes dated 24.8.2007 & 22.01.2008 recommended that the location of spillway on the left flank as proposed at feasibility stage of the project is preferable to centrally located spillway. However, this may still need a review at pre-construction stage to minimize rock excavation for approach channel. Earlier in the FR, the FRL and MWL of the dam were considered at 287 m & 288 m respectively. Now, at DPR stage, the FRL and MWL have been kept the same at 288 m.
2.0.1.2 Tunnels and Power House I & II
The location of Power House (PH-I) and tail race channel proposed at left side of spillway at FR stage has been relocated by Hydel Civil Design (NW&S) Directorate, CWC and GSI to the right side of the spillway in view of geological condition, available space and reduction in the length of tail race channel. Its installed capacity (2X30 MW) will, however, remain the same.
At feasibility stage, the aspect of providing water to KMPP command (Ken command) of M.P. through Daudhan dam was not studied in the absence of detailed information in respect of the command. The general impression was that water for Ken command in M.P. portion would be withdrawn from Bariarpur head works only. However, after receipt of detailed surveyed sheets of KMPP command (prepared by Survey of India) and other relevant records from State Govt., this aspect was examined in detail. It was decided to introduce an additional tunnel, named as lower level tunnel from Daudhan dam to connect the proposed LBC of KMPP (for which the detailed surveys and investigations had already been carried out by Govt. of M.P.) for providing water to major part of its command. The Power House (PH-II) proposed at the exit of tunnel providing water to Ken-Betwa link (now renamed as upper level tunnel) has been shifted to the exit of lower level tunnel in view of availability of water for longer duration and possibility of generation of more power due to increase in the head. The proposed installed capacity of PH-II is 3X6 MW. After generation of power in PH-II, the water will be released through 1.929 km long canal connecting to proposed LBC of KMPP. The alignment of Ken LBC as per surveyed maps collected from State Govt. has been modified in the initial reaches so as to meet the requirement of its command from Daudhan dam. During the periods when PH-II is not being operated owing to constraint of minimum head requirement, the waters meant for Ken LBC command are proposed to be passed through a byepass channel taking from lower level tunnel.
2.0.1.3 Link Canal
The link canal has been realigned considering no. of alternatives for its optimization in the reach from RD 94.65 km to RD 215.8 km (RD’s of FR stage) for minimizing the deep cutting. Its off take FSL has been lowered to 257 m now from 259 m as proposed in FR.
2.0.1.4 Upper Betwa Projects
The locations and types of the proposed projects in Upper Betwa basin component of the link project have now been finalised by NWDA in consultation with WRD, Govt. of MP. As per the suggestion of the State, the dam site earlier proposed at Neemkheda on Betwa River has now been shifted 7 km upstream of it to Makodia due to its advantages of less submergence, avoiding submergence of National Highway and higher level command. The locations of Kesari dam and Barari barrage have not been changed. But, at Kesari, in place of a dam as considered in FR, a barrage is proposed now. Also, Richhan dam proposed at the feasibility stage has been dropped in view of less catchment area and non-availability of adequate quantum of water for utilisation.
2.1 Topographical Surveys
Surveys & Investigations for the Ken-Betwa link project
Various field surveys & investigations viz. Topographical, Geological, Construction material, Geo technical investigations & Borrow area surveys (soils) for dams and canals, etc. in respect of Daudhan dam, Ken-Betwa link canal and Upper Betwa projects have been carried out as per the Terms of reference for preparation of DPR of Ken-Betwa link project, 2006 and guidelines given in the Working Group Report for preparation of DPR prepared by the erstwhile Ministry of Irrigation, Govt. of India, 1980.
2.1.1 Topographical surveys for Daudhan dam and Link Canal
(i) Survey for Transferring GTS Bench Mark levels
The proposed Daudhan dam and the initial reach of Ken-Betwa link canal are located in Chhatarpur and Panna districts of M.P. Field survey works were started by transferring nearby GTS bench mark value available with Survey of India on the Chhatarpur- Panna Road where the link crosses this road near the kilometre stone No. 47/4. The work of establishing adequate number of Permanent Bench marks (PBM) at different locations by precision levelling was carried out departmentally by connecting the nearest GTS B.M. already established by SOI in the vicinity of the project. The GTS B.M. was connected to the dam as well as link alignment and also to different components of the project including Upper Betwa projects, by precision levelling using double levelling method. The locations of permanent bench marks established in and around the project site are given in Annexure: 2.1.
Brief particulars of the various topographical surveys carried out for different components of the project are given below:
2.1.1.1 River
During the feasibility stage, the portion of Ken River between the proposed Daudhan dam axis and the existing Gangau weir had been surveyed. Chain and compass surveys parallel to the centre line of the Ken River either on the left bank or the right bank were done. Levels were taken at an interval of 25 m by double levelling and deepest bed level was connected. The cross sections of the river at every 200 m interval were taken upto HFL+2m on either side of the firm bank with the help of soundings technique for measuring the depth of water in the river at 25 m interval along each cross section line. The aim of this survey was to determine the capacity of the pondage between the Daudhan dam and the existing Gangau weir, which was proposed to be utilised as the tail pond for the pumped storage scheme (Power House-I). The purpose of this survey was also to find suitable location of Power House-I and Tail Race Channel. The L-section of this portion of Ken river are placed as Plate: 2.1.1 in Drawing volume-I.
In addition to the above, at DPR stage, cross section survey of river Ken has been carried out in d/s portion of the Daudhan dam up to Banda as desired by National Institute of Hydrology, Roorkee for carrying out the dam break analysis and other hydrological studies of this project. In total, 18 number of river cross sections in the downstream of proposed dam site have been taken across Ken River between Daudhan dam and Banda up to HFL + 2m on both river banks. These cross sections have been plotted in 1:2500 H and 1:100 V scale and supplied to NIH, Roorkee. The Drawings of these 18 cross sections are given as Plate.2.1.2 in the Drawing Volume-I. No river survey in the upstream of Daudhan dam has been carried out. The Survey of India (SOI) maps available for Ken Multipurpose Project (KMPP) have been used to generate the river longitudinal and cross sections and supplied to NIH for back water computations.
2.1.1.2 Reservoir
Madhya Pradesh Water Resources Department had formulated Ken Multipurpose Project (KMPP) during 1965. This KMPP project was proposed about 200m d/s of existing Gangau weir across river Ken. Survey of India had carried out submergence area survey of this project during the period 1965-67 on the request of Madhya Pradesh Water Resources Department (MPWRD). Submergence area maps, in the scale of 1:15846 (1 inch to 1 mile) showing contours from RL 234.6 m to 295.5 m (770 ft to 970 ft) with contour interval of 3.048 m (10 ft), available with MPWRD, have been collected by NWDA. These maps have been utilized by National Water Development Agency for preparing the submergence area maps of Daudhan reservoir as Daudhan dam is proposed on Ken river about just 2.7 km u/s of Ken Multipurpose Project with MWL/FRL at 288 m.